1. Field of the Invention
The invention relates to a vehicle control device, and more particularly, to a control device of a hybrid vehicle that is provided with an internal combustion engine, a power generator capable of input and output of motive power, a planetary gear mechanism in which three rotational elements are connected to three shafts, namely a drive shaft that is coupled to an axle, an output shaft of the internal combustion engine and a rotating shaft of the power generator, and an electric motor that inputs and outputs motive power to/from the drive shaft.
2. Description of Related Art
Conventionally, as such control devices of hybrid vehicles provided with an engine, a motor generator, and a motive power splitting mechanism that is connected to an axle, an output shaft of an engine and a rotating shaft of a motor generator, control devices in which the engine revolutions at an engine operation point for avoiding a rattling noise are set to be higher as the proportion of exhaust gas recirculation (EGR rate) becomes greater have been proposed (for instance, Japanese Patent Application Publication No. 2010-179856 (JP-2010-179856 A)). In this device, the engine revolutions at the engine operation point are set to be higher as the EGR rate becomes greater; as a result, occurrence of rattling noise is suppressed.
Control devices of a hybrid vehicle configured similarly include devices wherein the operation of an engine is controlled by setting an operation line in which the higher the vehicle speed is, the greater the torque is at a low rpm region of the engine (for instance Japanese Patent Application Publication No. 2007-022296 (JP-2007-022296 A)). In this device, there is masked abnormal noise that may occur through operation of the engine at a low-rpm, high-torque region, in that the higher the vehicle speed is, the greater travel-derived noise becomes. Discomfort to the driver caused by abnormal noise is suppressed as a result of that masking. However, control device of the hybrid vehicle has room for improvement in terms of improving the fuel economy while avoiding the occurrence of abnormal noise.